Operating mechanism for oil switches



July 19, 1932. J. N. KELMAN OPERATING MECHANISM FOR OIL SWITCHES Filed Feb. 1, 1928 ZSheetS- SheBi ZA/fBA/TOR:

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Patented July 19, 1932 UNITED STATES PATENT OFFICE JOSEPH N. KELMAN, OF LOS ANGELES, CALIFORNIA, ASSIGNOR TO KELMAN ELECTRIC &, MANUFACTURING COMPANY, OF LOS ANGELES, CALIFORNIA, A CORPORATION OF CALIFORNIA OPERATING MECHANISM FOR OIL SWITCHES Application filed February 1, 1928. Serial No. 251,161.

. My invention relates to electrical switches, and more particularly -to a novel operating mechanism for an oil switch.

merged in oil of suitable dielectric strength.

When it is desired to break the circuit, these contacts are separated, and the oil quickly quenches any are that may be formed when the contacts are separating. It is desirable to eilect a quick separation of the contacts when breaking high potential circuits. I have found that a heavy spring may be utilized to quickly openthe switch.

It is an object of my invention to provide a switch having a pair of engageable contacts, these contacts being quickly separable by means of a spring to open the circuit.

The use of such a spring often requires that a suitable stop mechanism be employed.

Inasmuch as the spring imparts high kinetic energy to the moving contact, this kinetic energy must be dissipated in stopping the movement of the contacts. The contact is usually quite massive, and a rigid stopping member will often be'broken due to the impact therewith of the moving contact. I have found a suitably designed dashpot to be efiective in thus absorbing the kinetic energy of the moving contact.

It is an object of my invention to provide a dashpot adapted to limit the motion of a movable switch contact when this contact has disengaged another switch contact.

This combination of a spring and a dashpot is particularly advantageous in an oil switch of the pantograph type. This type of switch has a pair of contacts adapted to be bridged by blades actuated by a pantograph.

It is an object of my invention to provide a pantograph-operated switch in which a spring and a dashpot act in conjunction with each other between opposite corners of the pantograph.

A further object of my invention is to provide a novel type of dashpot.

Still further objects and advantages of my invention will be made evident hereinafter. Referring to the drawings in which one embodiment of my invention is sho-wn,

Fig. 1 is a vertical sectional view of an oil switch incorporating my invention.

Fig. 2 is an enlarged elevational view of a portion of the pantograph mechanism when the switch is in a closed position.

Fig. 3 is a sectional view showing the details of the dashpot of my invention when the switch is in an open position.

Fig. 4 is a horizontal sectional view taken along the line 44C of Fig. 2. o

Referring particularly to Fig. 1, the oil switch of my invention is encased in a shell 11, this shell comprising a cylindrical side wall 12 closed at its lower end by a lower plate 13 and at itsupper end by an upper plate 14. Suitably supported, as by angleirons 16, is a supporting structure 17.

Mounted on opposite ends of the supporting structure 17 are primary and secondary insulators 18 and 19. Supported respectively on the primary and secondary insulators 18 and 19 are primary and secondary main contacts 21 and 22, these contacts being in the form of clips. Each main contact is connected to a conductor 23 extending upward through a suitable insulator in the upper plate 14. Adapted to engage the main contacts 21 and 22 are'primary and secondary blades 24 and 25, these blades being pivoted to a movable connector 27 by suitable pins 28. Primary and secondary links 30 and 31 are pivoted respectively to the primary and secondary blades 24 and by suitable pins 32 and 33. The lower end of each of the links and 31 is pivotally connected to a stationary connector 34 by a pin 35, this stationary connector being secured to a central insulator 37 mounted on the supporting structure 17. The blades 24 and 25, the links 30 and 31, and the connectors 27 and 34 cooperate to form a pantograph mechanism 40, this pantograph mechanism being adapted to open and close the contacts of the oil switch 10 by bridging these main contacts.

The movable connector 27 is secured to a link 42, this link being pivoted to a lever 43 by means of a pin 44%. The lever 43 is *and the main contact.

25 to move inward out of contact with the main contacts 21 and 22, as indicated by the dotted line osition 50. The shell 11 is filled with a suita le oil of high dielectric strength to a level indicated by the numeral 51.

A heavy coil spring 55 is adapted to be compressed between the movable connector 27 and. the stationary connector 34, this .spring being compressed when the switch is closed. The actuating mechanism 49 is adapted to receivethe thrust exerted by the s rin 55 and is so arran 'ed that b tri vin b O 2.)

this actuating mechanism 49, the spring 55 is allowed to quickly expand, thus carrying the pantograph into the position indicated by the dotted lines 50, and thus opening the switch. The spring 55 is made sufficiently strong so that a very quick acceleration of the blades 24 and 25 takes place, thus effecting a very quick break between the blades It is desirable that this speed of break be made as fast as possible in all high tension switches.

The spring 55 imparts a high kinetic energy to the pantograph mechanism when the switch is tripped. It is desirable to dissipate this energy as the blades move inward after breaking contact with the main con tacts 21 and 22. This I accomplish by means of a dashpot 57. The dashpot 57 is adapted to extend inside the coil spring 55, and is operated bythe movement of the connector 27 relative to the connector 34.

As best shown in Figs. 2 and 3, this dashpot 57 comprises a cylinder 58 which is threadedly received in a socket of the stationary connector 34. The upper end of the cylinder 58 is closed by a suitable plug 60 which is threaded therein and soldered or welded in place. Extending through an opening 61 in the plug 60is' a piston rod 63, the upper end of this piston rod being threadedly received in a socket 64 of the movable connector 27. Secured to the piston rod 63 inside the cylinder 58 is a suitable piston 67, this piston forming a tight sliding lit with the interior walls v upper perforations 7 2, 73, and 74, these perforations being increasingly smaller than the intermediate perforations 71 in a. direction toward the plug 60.

When the switch is closed, the dashpot mechanism is in a position indicated in Fig. 2, and the piston 67 lies near the lower end of the cylinder 58. WVhen the switch is tripped, the spring 55 forces the movable connector 27 upward at a high rate of speed, thus drawing the piston 67 upward in the cylinder 58. A portion of the oil in the shell 10 has entered the cylinder 58 through the perforations therein, so that this upward movement of the piston forces oil outward through these perforations as the volume between the piston 67 and the plug 60 is decreased as the connector 27 is moving upward. It should be clear that when the piston is in the lower part of the cylinder, a movement of the piston relative to the cylinder will be relatively easy, inasmuch as there are a large number of perforations above the piston which can carry oil from the interior of the cylinder to the exterior thereof. So, also, as the piston moves upward, oil may flow with ease into the lower end of the cylinder 58 through the lower perforations 70. As the piston moves upward, however, it successively passes over.

the intermediate perforations 71, thus successively decreasing the number of perforations available to carry oil from the interior of the cylinder to the exterior thereof. This retards the upward movement of the piston 67,

this retarding force becoming greater as the piston 67 approaches its uppermost position. lVhen in this uppermost position, the oil entrapped between the piston 67 and the plug 60 may escape only through the small perforation 7 4. Thus, the piston 67 is free to move when in the lower position of the cylinder 58, but is acted upon by an ever-increasing retarding force as it nears its uppermost position. the kinetic energy given to the pantograph mechanism by the spring 55, and the movable connector 27 is appreciably arrested as it nears its uppermost position.

By suitably designing the size and position T ofthe perforations, a very satisfactory dashpot action is obtained. The amount of retarding action will, of course, depend upon the viscosity of the oil as well as the size and position of the perforations. Such a dashpot may be used in other arts, and I am not limited to its use in an oil switch.

I claim as my invention:

1. In an electrical switch, the combination of: a pair of main contacts 5 blades adapted to bridge said main contacts; a movable connector to which said blades are pivotally connected; a stationary connector; links pivoted to said stationary connector and to said blades; a spring acting between said stationary connector and said movable connector to effect a quick separation of said blades and said main contacts; and a dashpot acting between said stationary connector and said movable connector to check the This retarding action dissipates movement of said movable connector, said dashpot acting as a guide for said movable connector.

2. In an electrical switch, the combination of: a pair of main contacts; blades adapted to bridge said main contacts; a. movable connector to which said blades are pivotally connected; a stationary connector; links pivoted to said stationary connector and to said blades; a spring acting between said stationary connector and said movable connector to efiect a quick separation of said blades and said main contacts; a cylinder; and a piston operable in said cylinder in response to a movement of said movable connector, said cylinder and said piston comprising a guide for said movable connector and a dashpot mechanism.

3. In an electrical switch, the combination of: a pair of main contacts; blades adapted to bridge said main contacts; a movable connector to which said blades are pivotally connected; a stationary connector; links pivoted to said stationary connector and to said blades; a spring acting between said stationary connector and said movable connector to efl'ect a quick separation of said blades and said main contacts; a perforated cylinder; a plug in the opposite end of said cylinder; a piston rod extending through said plug, said piston rod being connected to said movable connector and extending between said movable connector and said stationary connector; and a piston secured to said piston rod in said cylinder, said piston and said cylinder being relatively movable when said movable connector moves relative to said stationary connector, and said piston and said cylinder comprising a dashpot mechanism and a guide for said movable connector.

4. In an oil switch, the combination of: a shell, said shell containing an oil; a pair of main contacts mounted in said shell submerged in said oil; blades adapted to bridge said main contacts; a movable connector to which said blades are pivotally connected; a stationary connector; links pivoted to said stationary connector and to said blades; a coil spring between said stationary and said movable connector, said spring acting to effect a quick separation of said blades and said main contacts; a stationary cylinder extending inside said coil spring, said cylinder containing perforations permitting said oil to enter said cylinder; a plug in the upper end of said cylinder; a piston rod extending through said plug, said piston rod being secured to said movable connector; and a piston on said piston rod in said cylinder, said piston being adapted to decrease the volume of said cylinder between said plug and said piston when said blades are moving from contact with said main contacts, the oil in said decreasing volume being forced through said perforations.

5. In an electrical switch, the combination of: a pair of main contacts; blades adapted to bridge said main contacts; a movable connector to which said blades are pivotally connected; a stationary connector; links pivoted to said stationary connector and to said blades; and a dashpot acting between said stationary connector and said movable connector to check the movement of said movable connector, said dashpot acting as a guide for said movable connector.

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 27th day of January, 1928.

JOSEPH N. KELMAN. 

